Electron Mobility in GaSb at 77°K

Electron mobility (more specifically, the product $R\sigma$ of the Hall coefficient and the conductivity) has been measured in $n$-type GaSb at 77°K as a function of carrier concentration and for several densities of compensating acceptors. Throughout the region where conduction is confined essentially to the principal conduction-band minimum, a good quantitative fit to the data is obtained by consideration of ionized-impurity scattering only, under conditions of compensation. Evidence suggests the compensating centers to be doubly ionized and of a density equal to that of the residual acceptors existing in the initial $p$-type material before it was doped to $n$ type. Such results are also quantitatively consistent with findings of ion-pairing studies involving lithium. At higher carrier concentrations, where conduction in the [111] subsidiary band becomes important, theoretical predictions are rendered more difficult by uncertainties in parameters characterizing the [111] band, as well as other complicating effects such as screening and the scattering of [000] electrons upon [111] electrons. Semiquantitative agreement, however, tends to favor, for $\Delta E$ and $\frac{{m_1}^d}{{m_0}^d}$, the lower values that were previously published.